MIPS: JZ4770: GCW0: Removed initialization of mystery GPIO pins

GPE8 is reset for the ETH MAC PHY on the Pisces board, but has no
function on our board.

GPB28 doesn't seem to be used for anything.
MIPS: JZ4770: Make board responsible for registering platform devices

Which devices are desired can differ per board. We already had some
platform devices registered by the board and some by the platform
code; now all are registered by the board, like on the JZ4740.
MIPS: JZ4770: GCW0: Register platform devices
MIPS: JZ4770: GCW0: defconfig: Enable ALSA MIDI sequencer

This is useful for supporting timidity++ in daemon mode.
USB: ohci-jz4740: Tentative fix for hub control

Needs verification by larsc.
MIPS: JZ4770: GCW0: Model the WiFi power pin as GPIO regulator for vbus

Since the WiFi module is the only device on the bus, power for the bus
and power for the device are the same thing.

Note that this pin disables the entire WiFi module, not just the radio
part, so rfkill is not the right way of modeling it in the kernel.
MIPS: JZ4770: GCW0: defconfig: Enable power regulator drivers
MIPS: JZ4770: GCW0: Use minimal gpio header in board setup code